Oil Pump Replacement

Fig. 22 Oil pump components:

It is necessary to remove oil pan, oil pickup and chain case cover (CCC) to service oil pump rotors. The oil pump relief valve can be serviced by removing oil pan and oil pickup tube.

Fig. 23 Oil pressure relief valve components:

DISASSEMBLY

1. Remove relief valve as follows:
a. Drill a 1/8 inch (3.175 mm) hole into relief valve retainer cap, then insert a self-threading sheet metal screw into cap.
b. Clamp screw in a vise, then while supporting chain case cover (CCC), remove cap by tapping CCC with a soft hammer.
c. Discard retainer cap, then remove relief spring and relief valve.
2. Remove oil pump cover screws, then lift off cover.
3. Remove pump rotors.
4. Wash all parts in a suitable solvent and inspect for damage or wear.

INSPECTION & REPAIR

1. Clean all parts thoroughly. Mating surfaces of CCC should be smooth. Replace pump cover if scratched or grooved.

Fig. 24 Measuring oil pump cover flatness:

2. Lay a straightedge across pump cover surface. If a 0.003 inch (0.076 mm) feeler gauge can be inserted between cover and straightedge, cover should be replaced.

Fig. 25 Measuring outer rotor thickness:

3. Measure thickness and diameter of outer rotor. If outer rotor thickness measures 0.3005 inch (7.36 mm) or less, or if diameter is 3.141 inches (79.78 mm) or less, replace outer rotor.

Fig. 26 Measuring inner rotor thickness:

4. If inner rotor thickness measures 0.301 inch (7.64 mm) or less, replace inner rotor and shaft assembly.

Fig. 27 Measuring outer rotor clearance in case:

5. Install outer rotor into CCC, press one side with fingers and measure clearance between outer rotor and CCC. If measurement is 0.022 inch (56 mm) or more, replace CCC only if outer rotor is within specifications.

Fig. 28 Measuring clearance between rotors:

6. Install inner rotor into CCC, then measure clearance between inner and outer rotors. If clearance measured between rotors is 0.008 inch (0.203 mm) or more, replace both rotors.

Fig. 29 Measuring clearance between rotors & case:

7. Place a straightedge across face of CCC between bolt holes. If a feeler gauge of 0.004 inch (0.102 mm) or more can be inserted between rotors and straightedge, replace pump assembly.
8. Inspect oil pressure relief valve plunger for scoring and free operation in it's bore. Small marks can be removed with 400-grit wet or dry sand paper.
9. Relief valve spring has a free length of approximately 1.95 inches (49.5 mm) and should test between 19.5-20.5 pounds when compressed to 1-1/32 inches (34 mm). Replace spring that does not meet specifications.

ASSEMBLY & INSTALLATION

1. Assemble oil pump as shown, using new parts as required.
2. Tighten oil pump cover screws to specifications.
3. Prime oil pump prior to installation by filling rotor cavity with engine oil.
4. Refer to procedure described under TIMING CHAIN COVER & OIL SEAL to install timing chain case cover.